1. Field of the Invention
The present invention relates to library apparatuses, and in particular, relates to a library apparatus including a cartridge type sensor, the sensor, and a method for positioning the sensor at a predetermined location in the library apparatus. The cartridge type sensor includes a cartridge having the same shape as that of each recording medium to be stored in a cell, an optical reader, and a medium detector, the optical reader and the medium detector being arranged in the cartridge. In the library apparatus, the cartridge type sensor is stored in any of cells for storage of recording media. The sensor is removed from the cell and is then positioned in order to read a medium identification code and/or detect the presence or absence of a recording medium in a target cell while being held.
2. Description of the Related Art
With the recent increase in capacity of a hard disk, the loss of data has more serious effects beyond an individual or a company.
In case data is lost, therefore, backup of systems is of the most importance to computer operation. In many cases, a library apparatus for magnetic tapes or optical disks, serving as recording media, is used for backup of data.
In the library apparatus, magnetic tapes or optical disks, each of which is housed in a cartridge, are stored in respective cells of a cabinet. A robot provided for the library apparatus removes a target recording medium from a cell, carries the medium, and inserts it into a drive for recording/playback.
In addition, the robot ejects the recording medium from the drive, carries the medium, and returns it into the original cell.
Generally, a library apparatus for magnetic tapes stores several to hundreds of magnetic tapes and includes one or more drives and one or two robots.
A conventional library apparatus will now be described in more detail.
FIGS. 8A to 8C are diagrams explaining a conventional library apparatus. FIG. 8A is a perspective view of the library apparatus as viewed from the front side. FIG. 8B is a perspective view of the library apparatus as viewed from the rear side. The library apparatus has a front door 110 and a rear door 120 and also includes cells, a robot, and a drive. The front door 110 includes an insertion-ejection mechanism 130, through which a recording medium is inserted or ejected. FIG. 8C is a cross-sectional view at the line A-A′ of FIG. 8B. In the library apparatus, a U-shaped cabinet 141 including a plurality of cells 140 is arranged, i.e., segments of the cabinet 141 are arranged on left, right, and back walls, respectively. In each segment, shelves are arranged vertically. A drive 150 is disposed under the lowermost shelf of the back segment of the cabinet 141. The insertion-ejection mechanism 130 is arranged on the rear of the front door 110. A robot 160 is located in substantially the middle of the apparatus.
FIGS. 9A and 9B are diagrams explaining the structure of the robot 160. FIG. 9A shows the whole appearance of the robot and a Y mechanism 161. FIG. 9B shows lower part of the robot 160 and illustrates an X mechanism 162, a Z mechanism 163, and a rotating mechanism 164. FIG. 9B also illustrates a hand 170 for removal and storage of a recording medium from/into a cell 140 and for insertion and ejection thereof into/from the drive 150. The X to Z mechanisms and the rotating mechanism are configured to position the hand 170 at a target cell 140, the drive 150, or the insertion-ejection mechanism 130. The Y mechanism 161 is vertically movable. The X mechanism 162 and the Z mechanism 163 are horizontally movable. The rotating mechanism 164 is horizontally rotatable.
FIG. 10 is a diagram explaining the hand 170. The hand 170 includes a picker 173, a CCD camera (or a laser barcode reader) 171, a medium detector 172, and a holding mechanism (not shown). The picker 173 picks up a recording medium 200 from a cell 140. The CCD camera reads a medium identification barcode applied on the recording medium 200. The medium detector 172 detects whether the recording medium 200 is stored in the cell 140. The holding mechanism holds the recording medium 200 picked up by the picker 173.
FIG. 11 is a diagram explaining barcode reading.
For instance, when the library apparatus is turned on after maintenance, in order to check whether a recording medium has accidentally been ejected from or inserted into the apparatus during maintenance, the medium detector 172 detects whether each cell 140 stores a recording medium 200 in the library apparatus upon power on and the CCD camera 171 reads a barcode 201 applied on each recording medium 200, thus controlling the storage of media in the library apparatus. In a typical library apparatus capable of storing several hundreds of recording media, the medium detector 172 and the CCD camera 171 are mounted on the hand 170 in order to reduce the time required for checking upon power on.
FIG. 12 is a diagram explaining detection of a mark (hereinafter, referred to as a flag) for position correction. The robot 160 uses a flag in order to ensure the accuracy of positioning to a target cell 140 or the drive 150. FIG. 12 illustrates the robot 160 which reads a flag applied on a recording medium cartridge stored in a cell. Flags are also applied on predetermined positions in, e.g., frames of the respective cells 140, the drive 150, and the insertion-ejection mechanism 130. The CCD camera 171 is used to read the flags. In the use of the CCD camera 171, barcode reading and flag reading are performed by the single camera.
Related arts include another type of library apparatus and a method for the same. This conventional library apparatus includes a cartridge-shaped unit for internal monitoring of the library apparatus. The cartridge-shaped unit includes a cartridge having the same shape as that of each recording medium and further includes therein a camera, a transmitter, and a battery. A receiver and a monitor are arranged outside the library apparatus. According to this conventional method, the camera captures an image of the internal state of the library apparatus to output video signals, the transmitter transmits the video signals, the receiver receives the signals, and the monitor displays the received signals.
The purpose of this method is to confirm the internal state of the library apparatus without opening a door under abnormal conditions, e.g., when a recording medium cartridge falls in the library apparatus.
As described above, in the foregoing conventional apparatus, the CCD camera 171 and the medium detector 172 are mounted on the top or bottom of the hand 170, alternatively, the left or right side thereof. In addition, the CCD camera 171 has to be accurately installed on the hand 170 in order to ensure the positioning accuracy of the robot 160. The above-described arrangement causes a large dead space in the library apparatus.
FIGS. 13A and 13B are diagrams explaining examples of a dead space. Referring to FIG. 13A, in a case where the CCD camera 171 and the medium detector 172 are mounted on the top of the hand 170, the CCD camera 171 has to be opposed to a barcode 201 applied on a recording medium 200 stored in a lowermost cell 140 to read the barcode 201. Unfortunately, a large dead space is created as shown in the figure. Disadvantageously, the dead space leads to a reduction in the number of stored recording media.
FIG. 13B illustrates detection of the presence or absence of a recording medium 200. Though smaller than that in reading the barcode 201, a dead space is created in this case. When two robots are mounted for redundant arrangement of robots, two CCD cameras 171 and two medium detectors 172 are needed. This results in an increase in cost.
The other conventional method has an advantage that abnormal conditions can be observed without opening the door because the camera arranged in the cartridge-shaped unit captures an image of the internal state of the apparatus.
However, the conventional method does not intend to reduce a dead space. In addition, the method does not intend to reduce the cost of a library apparatus with two robots.
According to the present invention, it is an object to provide a library apparatus capable of reducing the above-described dead space and including one CCD camera and one medium detector when two robots are arranged.